Electric heating unit for sandwich toasters



Oct. 19, 1937. J1 J. GOUGH 2,096,582

ELECTRIC HEATING UNIT .FOR SANDWICH TOASTERS Filed Feb. 20, 1937 2 Sheets-Sheet 1 liv 2 M" J5me; c 7% Oct. 19, 1937. J J,GOUGH 2,096,582

ELECTRIC HEATING UNIT FOR SANDW1CH TQASTERS Filed Feb. 20, 1957 2 Sheets-SheetZ I van 601' J2me, J7

.datented Oct. i9 1937 a UNITED STATES PATENT OFFICE v I spouses usc'rnro m'l'mGzUTlglgs non smwrcn TOAS James J. Gough, Chicago, 11]., assignor to Chicago Electric Manufacturing Company, Chicago, 111., a corporation of Illinoisv k Application February 20, 1931, Serial No. 120,010 1: Claims." (01. 210 -19) My invention relates to an electric heating unit particularly adapted for radiating heat toward an adjacent surface, as for example to .a grid of an electric sandwich toaster or an electric waine iron: and more particularly-to an electric heating unit of this-general class in which a heat-radiating high resistance wire is looped over insulators mounted on a supporting member, and in which the looping of the wire over'th'e insu- 10 lators also retains theinsulators in their proper.

supported positions. I

In its general objects myinvention aims to provide an unusually simple, speedily assembled and inexpensive heating unit of the above recited type, and one which will be so positioned by its mere insertion in the corresponding portion of an appliance as to the heating wire for radiating its heat fairly uniformly toward the grid or other surface which is to utilize the heat.

More particularly, my invention aims to provide a light and simple heating unit including a a simple resilient loop of high resistance wire sup- ;ported within a frame of considerably'smaller area (in the general plane of the frame) than the compartment of the appliance housing the unit, and including insulators'over which the said loop is hooked, the insulators being slidably attached to the frame and held in their operative positions by the tension of the said loop.

" In addition, my invention aims to-provide electric unit of the above recited characteristics,

in which adjacent'insulators of counterpart size and shape can readily be supported either in a counterpart positions for facilitating the interlooking ofthe insulators with a heating wire which is to be used at-a moderate temperature,- or in relativebinverted positions when the heat-'- ing wire isto be raised to so much higher temperature that the expansion of this wire might 40 .bulge it out of interlocking relation to an .insulater. 1 Y

with household electric appliances such as waf-.

. fle irons or' toasters .havim horizontal grids, the

cost of the needed heating units heretofore has been undesirably high. for the following reasons:

(1) Because of the quite rigid structure re-.

quired for the supporting member on which the insulators are mounted,-.and the undesirably high cost of manufacturing this member, For exam- I pie, if the wire is aimed over insulators mounted on cross-bars spanning two side rails, the construction of a rigid side rail and cross-bar asfor this purmsqhes q d rather thick metal punching, usually made from a blank 6 corresponding in area'to the interior cross-section of the casing section of the appliance in which the heating unit is disposed. In addition, such a single-piece structure requirescorrespondingly large and expensive dies for both the blanking and the forming operations. 5' v With the cross-bars formed separately from the side rails, the cost and weight of the needed metal is reduced, but the firm attaching of the said bars to the rails adds considerably to the manufacturing expense, and' the: same occurs 10 when the cross-bars span a cbmplete framea In a third type of supporting members, the Y insulators have been supported in" relatively staggered'dispositlon onoppositeside bars of a frame.

-But in this case the frame-likewise has tobe 15. heavy and rigid to prevent the tensioning of the wire, when ilooped in zigzag formation over insulators alternately mounted on one and the other of the said bars, from bowing these bars toward each other so that loops of the -wire may snap zo off one or more of the, insulators when the wire elongates during its rise in temperature.

(2) Because of the frequently considerable cost of mounting the insulators on the supporting member.

' (3) Because the undesirably increased weight of an entire unit of the above recited three types adds to the shipping weight and transportation cost of the appliance equipped with such a unit, since the manufacturer commonly pays the trans- 30 ,portation to the larger distribution points for his products.

My present invention aims to overcome all of the above recited shortcomings of the now commercial heatingunits of the above recited 'gen- 35 eral class by using a simple metal frame as the member which supports the needed insulators; by I constructing this frame of a-metai strip bent "flatwise; by providing this frame with integral.

sitioned on the frame; and by disposin the said 50 wire so that its tensioning will not bow any vframe side inwardly, thereby permitting theframe to be-made from a rather thin strip of metal.

Moreover, my invention aims'to provide an ina sulator-supporting frame of the just recited characteristics which can readily be constructed of the frame from the riser wall of the compartment in whichthe heating unit is to be'disposed.

Illustrative of the manner in which I plishthe objects of my invention, v

Fig. 1 is a plan view of an electric heating unit embodying my invention, showing this as it appears when disposed in the rectangular lower casing section of a sandwich toaster.

Fig. 2 is a vertical section taken along theline 2-2 of Fig. 1 and including a) part of apanaccomshaped grid supported by and within the mouth portion of the illustrated casing section.

Fig. 3 is a vertical section taken along the line 3-3 of Fig. 1.

Fig. 4 is an enlarged and fragmentary horizontal section taken along the line 6-6 of Fig. 3, showing the interlocking of adjacent end portions of the two frame halves.

Fig. 5 is a similarly enlarged vertical sectiorr taken alongthe line 5-5 of Fig. 1 through one of the oblique corner portions'of the frame. Fig. 6 is a perspective viewof one of the wireloop supporting hooks, drawn on the same scale as Fig. 5. e Fig. 7 is an enlarged and fragmentary elevation, looking from the line 'I----'! of Fig. 1..

Fig. 8 is an enlarged ,perspective view'of one of the two counterpart halves of the frame of the heating unit of Fig. 1, before this is attached to the other frame half, thefigure also including anen'd portion of the relatively reversed-other atte ts ing from the tip of its end part E and extending both parallel to the main frame side part F and v in a direction away from the other end part E and each such end part B has a vertical slot S through which thefinger f on the companion frame half can be slidably inserted.

Each frame half also has a tab T projecting from the tip of its said other and part E and extending parallel to the mainframe side part F v same frame half.

When the two separately formed frame halves are set down on a fiat surface, with their ends relatively disposed as shown for one end of each in the right-hand portion of Fig. 8, the fragmentarily illustrated'frame part can readily be slid towardthe right for simultaneously causing the finger f of one frame half to extend through and outwardly beyond the slot S in the companion frame half, and sliding the tag T.of the said companion frame half through the slot S of the said one frame half.

Each .tab T is then clinched against the inner face of the frame portion E through which it ex tends, so that this clinching cooperates with the frame half as the latter appears when about to Fig. 9 is a fragmentary plan view allied to the midlength portion of the lower part of Fig. 1,

but showing the use of two relatively inverted hooks in place of the single one shownin the corresponding part of Fig. 1.

Fig. 10 is a fragmentary vertical section taken along the line illi 0 of Fig. 9.- v i Fig. 11 is a plan view of a circular casing section, such as the lower section of a waiile iron, and of acircular-framed two-part heating unit disposed-in the said section.

Fig. 12 is a reduced perspective view the. counterpart halves of the frame of the heat-' ing unitof Fig..11,' taken before that half was, interlocked with the c'ompanio frame half.-

"In the drawings, Figs. 1 to 3: ow a generally rectangular and pan-like lower'casing. section 0 of a sandwich toaster, and Fig. 2 as well as'Fig. 3 includes an end portion of a shallow pan-like grid G which spans the mouth portion of this casing section, and which grid has a peripheral flange F seated on the mouth end of that section.

-To heat the bottom C of the said casing section'I provide a heating unit including a 86 1- erally rectangular frame considerably shorter and narrower than the said section? This framenconsists of two relatively interlocked frame halves, each such frame half being a strip of steel bent flatwise toa generally semi-rectangular shape presenting a long frame side 'part F hayingfits ends connected respectively to two shorterframe ends E and E by connecting portions P and P each of which extends at an oblique angle to the frame parts which itconnects. I

Each suchframe half, in its "separate preliminary-shape'cf Fig. 8, hasrafinger f projectof one of slidabie interfitting of each tab T with a slot S in rigidly connecting the two frame halves. In addition, the fingers), when each of a length only slightly less than half the difference between the length of the complete frame and the interior length of the casing section C, space the frame ends equally from the ends of the said casing section. To space the frame also to an equal extentfrom each longitudinal riser side of the said casing section, I also form the main portion F of each frame half with auxiliary spacer fingers 3 projecting outwardly of the frame for a distance approaching half the difference between the near its mid-length with at least one upright slot 5, and desirably with three slots la, lcand 4d) as shown in Figs. 2 and 8; and I also provide.

a similar. slot 5 in each of the oblique frame corner parts P. These slots 4 and 5 preferably 8 for centering insulators I through which the r are all of counterpart size for receiving the shanks 1 of lava'. counterpart mica insulators each of which includes both a back I (Fig. 6) longer than 1 such a slot and a hook at H at the opposite end from the said shank.

To facilitate a suitable positioning of the ter-' minals i to which the ends of the heating wire are to be fastened, I also desirably form the midlen'gth portionof the-major. side F of each frame part with two centrally perforated annular bosses two wire terminalsextend in the usual manner.

With the fran eof my heating unit constructed in theheretofore recited manner, the two wire terminals 1 can be mounted on this frame before the ends of a suitable fength of the resilient (and desirably coiled) heating wire are respectively fastened to these terminals. Four of the insulators shown in Fig. 6 are then slid inwardly ofthe frame respectively through' th e slots 5' in the oblique cornerportions of the frame, and if thesaid wire is to be heated toonly such a lirnited temperature as not to expand it unduly in length. a is slid (inwardly of-the frame) partway through, amidlength slot in the frame side opposite the wire terminals, this last named insulator being shown 3 at the middle of Fig. 2.

when an of these-insulators have thus been slidably applied to the frame with their hook openings facing the loop (to'which the wire is bentwwhen its ends arefastened to'the two'wire terminals) can readily" be. stretched to snap it over the hook portion of. each insulator.

.While this fs'being done; the tensioning of the wire draws all of the hooks-inwardly of the frame until the projecting upper and lowerend portions is of thehook backs 1 (rig. e) bear mainst periph-I eral portions of the frame, as shown in Figs; 1 and 5, and this tension thereafter also holds the .wire interlocked with all of the hooks.

However, if the-resistance of the wire is con 20 siderably lower (in proportion to the voltage of the current supply, as is needed when the 'grid bottom G is to be heated to a correspondingly higher temperature, the elongation of the wire when thus heated might snap. the wire loop out 25 of the hook Ha of the insulator which is at the 1 middle 'of a relatively long stretch of the wire. To avoid this when my heating unit is to operate at such a high temperature I. then" employ two insulators havingtheir hooks Rb and He respec- 80 tlveLv extending through the slots 4a lb which are adjacent to (but at opposite sides of) the midlength slot .4, as shown in Fig. 10.

In doing this, I ailhr one insulator H]: with its hook *opening upward, and the other insulator jg. Kc with its hook opening downwards as shown 45 from the peripheraiwall of the casing, so that theheat radiated from this wire is distributed over the grid bottom G with a sufiicient uniformity for toasting purposes or the like. Moreover, when the frame of my 'unit is set on a substantially 50 horizontal casing section bottom C '(from which it may be insulated .by a customary-although not illustrated asbestos sheet overlying the said bottom), the frame also prevents a direct radiation of heat from the resistance wire tothe riser 55 wall of the casing section, thereby aiding me in obtaining an'eflective distribution of the heat over the .grid above this frame.

Since each of the heretofore described mime halves can be cheaply formed-by simple punch press operations from a simple strip of steel, only a single set of relatively small and inexpensive v dies is required for producing both of these frame halves. Likewise, since the extending of one tab T and one finger I through slots'adiacent to the overlapped end portions of the frame halves at each juncture of these halves latches these end portions against sliding with respect to each other, the simplebending of the two tabs '1 (from the position shown at T to the full line position in Fig.- 4), this operation alone completes the rigid assembly of'the frame.

With the length-of each lava insulator quite looped wire to. extend at a short angle to 75 th adjacent portion of the frame, lo'that the position of the tab T for rigidly connecting these effect of the tension of the ,wire is directed time longitudinally of each such frame portion. Con

sequently, the tensioning of the wire loop will not how the frame sides toward each other even when the frame is formed from a rather thin strip, as

' for example a strip inch wide and J; inch thick. This lightness of the strip not only greatly reduces the cost and weight of the supporting member of my frame, but also (when the strip is of a moderately resilient steel) allows the 10 frame to be digitally compressed so as to draw the spacer projections 3 and I somewhat toward each other. Such a momentary distortion of the frame is permitted all the more readily when the frame has the oblique corner portions P and P is instead of right angled corners, so that my frame can readily be flexed sufiiciently for inserting it' However, while l have heretofore described'my new electric heating. unit in connection with an 2' embodiment designed for use in a horizontally rectangular compartment, the shape of this unit can readily be varied tocorrespond to other sections of the compartment which is to house it. 'Ihus, Hg. 11 shows a heating unit of generally similar construction, as' disposed in the lower circular casing section it of an electric wanle iron, and Fig. 12 (on a reduced scale) shows one of the frame halves of this unit before it is attached to the companion rame half.

Ineach of the illustra d embodiments of my invention; the frame (which would function equally well, as far as the supportingof the insulators is concerned, if it did not have the radially proiecting spacer fingers j and 3) requires 3 less material than it would if of a size directly fitting the compartmenthousing it. Moreover, the extending of the finger f on each frame section through a slot of similar cross-section in the adjacent frame section co-operates with the disframe sections without requiring any firm fastening operation other than the clinching of the said tab as illustrated in Fig. 3. Moreover, it should be obvious that my heating unit can be of 5 quite small height. (transverselyof the general 1 plane of the frame) in proportion to thedimensions of the frame, thereby enabling it to be used in a'correspondingly shallow compartment. So also, while I have described my here presen ted heating unit as including many desirable details ofeconstruction and arrangement, these obviously might be varied in many respects without departing either from the spirit of my invention or from the appended claims.-

flclaim'asmyinvention:

1. An electric heating unit comprising a frame formed of ilatwise bent metal strip material, the frame having peripherally spaced slots extending at right angles to the general plane of the frame: insulators each including a hook part slidably inserted inwardly of the frame through one of the slots and also including a back part engaging the exterior of the frame; two circuit terminal members extending through and insulated'from adiacent portions of the frame; and a resilient loop of high resistance wire having its-emu connected respectively to the two terminals, the said wire extending consecutively through the hook parts of insulators which are consecutively disposed peripherally of the frame, and the backs of the "P I, said hooks being held against the exterior of the short in proportion to even the width of the, frame, I readily cause each stretch of electric heating unit as per claim 1, in-

framebythetensioningofthesaidwire. 7W

elements spaced circumferentially secutive insulators extends at a quite small acute angle to the frame portion adjacent to that wire stretch.

. 4. An electric heating unit as per claim1, in

which the frame comprises two parallel frame end parts, two parallel frame side parts extending at right angles to the said end parts, and framecorner elements each connecting the end of a frame end part with the adjacent end of a frame side part; each of the said corner elements ex tending obliquely to both of the frame parts which it connects, and being provided with one of the slots through which the said insulators extend.'

' 5. An electric heating unit as per claim 1, in which the frame is composed of consecutive frame sections, the adjacent ends of each two consecutiveframe sections being fastened to each other;

each frame section having spacer elements formed thereon, the said elements being spaced longitudinally of that section and extending outwardly away from the said frame.

6. An electric heating unit as per claim 1, in

which the frame is composed of consecutive frame sections, the adjacent ends of each two consecutive frame sections being fastened .to each other; each frame section having spacer elements fast thereon and spaced longitudinally of that section and extending outwardly of the frame; one of the spacer elements-on each frame section serving also as part of the means which fasten that frame section to an adjacent frame section. v 7. An electrieheating unit as per claim 1,-i which the frame is composed of consecutive frame sections, the adjacent ends of each two consecutive frame sections being fastened to each other;

each frame section including spacer elements fast thereon spaced longitudinally of that section and extending outwardly -'of the frame; each frame section having an auxiliary slot disposed near one end of that section and extending at right angles to the general plane of the frame, through which slot a spacer element of the adjacent section extends. v

8. In an electric heating unit, a frame formed of two fiatwlse bent strips extending consecutively in continuation'of one another, the adjacent end portions of each two consecutive strips being.

overlapped; insulators supported by and spaced mounted upon and insulated from the said frame; and a. resilient high resistance wire connected at its ends respectively to the said terminals within the said frame, the said wire extending consecutively through the hook portions of .the said ining a finger projecting from the tip of each strip end, the fingers at opposite ends of each strip extending substantially atright angles from the face of the adjacent face of the strip and respectively inward and outward of the frame, and the two fingers on each strip extending respectively through'the said slots in the end portionof the other strip.

9'. An electric heating unit as per claim 8, in which the free end portion of one of the inwardly extending fingers isclinched against a part of the strip having the slot through which that finger extends.

10. An electric heating unit as per claim 8, in which each strip also has atleast one spacer finger formed from the strip'and extending outwardly of the frame, the said spacer fingers being distributed peripherally of the frame and of such lengths as to dispose theirtips substantially within an imaginary contour conforming in shape to, but larger in dimensions,than the periphery of the frame.

11. An electric heating unit as per claim 8, in

which each strip also has at least one spacer finger formed from the strip and extending outperipherally 'of the frame and each presenting a hook portion within the frame; two terminals wardly of the frame, the said spacer fingers being distributed peripherally of the frame and of such lengths that the tips of these spacer fingers and the tips of the first named outwardly projecting fingers are all'in an imaginary contour conforming in shape to, but larger in dimensions, than the periphery of the frame.

12. An electric heating unit as per claim 8, in

which each strip also has at least one spacer fingerformed from the strip and extending outwardly of the frame; the said spacer fingers being distributed peripherally of the frame, and the tips of these spacer fingers as well as the tips of the" first recited outwardly extending fingers lie in a contour conforming in shape to, but larger in dimensions, than the periphery of theframe; the said strips being formed of sufficiently thin and resilient metal so that the frame can be manually flexed to dispose all of the said finger tips in a contour smaller than the aforesaid one.

- JAMES J. GOUGH. 

